////////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  Note:  tty Terminal Emulation program 
//
using System;
using System.Threading;
using Microsoft.SingSharp;
using Microsoft.Singularity;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.Io;
using Keyboard = Microsoft.Singularity.Io.Keyboard;
using Pipe = Microsoft.Singularity.Io.Tty;

namespace Microsoft.Singularity.Applications
{
    // See WaitForChildThread below
    internal contract WaitForChildContract {
        out message Finish();
        state Start: one {Finish! -> Done;}
        state Done: one {}
    }

    public class Tty
    {
        private static TRef<KeyboardDeviceContract.Imp:Ready> keyboardRef; 
        private static TRef<ConsoleDeviceContract.Imp:Ready> consoleRef; 
        private static TRef<UnicodePipeContract.Imp:READY> inputEp; 
        private static TRef<UnicodePipeContract.Exp:READY> outputEp; 
        private static char[] modTable;
        private static Process process; 
        private static Terminal terminal;

        private static void InitModTable()
        {
            modTable = new char[8]; 
            modTable[1] = '1'; 
            modTable[2] = '2'; 
            modTable[3] = '3'; 
            modTable[4] = '4'; 
            modTable[5] = '5'; 
            modTable[6] = '6'; 
            modTable[7] = '7'; 
        }

        public static KeyboardDeviceContract.Imp OpenKeyboard(string! devName,
                                                              DirectoryServiceContract.Imp! ns)
        {
            // get NS endpoint
            KeyboardDeviceContract.Exp! exp;
            KeyboardDeviceContract.Imp! imp;
            KeyboardDeviceContract.NewChannel(out imp, out exp);

            ErrorCode errorOut; 
            bool ok = SdsUtils.Bind(devName, ns, exp, out errorOut );

            if (!ok) {
                DebugStub.WriteLine("Console Input: OpenKeyboard lookup of {0} failed.",
                                __arglist(devName));
                if (imp != null) delete imp; 
                return null;
            }
            assert imp != null; 
            
            switch receive {
                case imp.Success():
                    break;
                case imp.ContractNotSupported():
                    throw new Exception("ConsoleInput: Contract not supported");
                    break;
                case imp.ChannelClosed():
                    throw new Exception("ConsoleInput: Didn't imp.RecvActConnect");
                    break;
            }
            return imp;
        }

        private static ConsoleDeviceContract.Imp OpenConsole(string! devName,
                                                             DirectoryServiceContract.Imp! ns)
        {
            ConsoleDeviceContract.Exp! exp;
            ConsoleDeviceContract.Imp! imp;
            ConsoleDeviceContract.NewChannel(out imp, out exp);
            ErrorCode errorOut; 
            
            bool ok = SdsUtils.Bind(devName, ns, exp, out errorOut); 
            
            if (!ok) {
                DebugStub.WriteLine("Console Input: OpenConsole lookup of {0} failed.",
                                __arglist(devName));
                if (imp != null) delete imp; 
                return null;
            }
           
            if (imp != null) {
                switch receive {
                    case imp.Success():
                        break;
                    case imp.ContractNotSupported():
                        throw new Exception("ConsoleOutput: ContractNotSupported");
                        break;
                    case imp.ChannelClosed():
                        throw new Exception("ConsoleOutput: ChannelClosed");
                        break;
                }
            }
            return imp;
        }
      
        private static char[]!  in ExHeap ProcessKey(uint key, [Claims] char[] in ExHeap buffer, out int len)
        {
            len = 0; 
            if (buffer == null) {
                buffer = new [ExHeap] char [10]; 
            }
            
            assert buffer.Length != 0; 
            
            //Console.WriteLine("processKey:{0:x}",key); 
            char c = (char)(key & (uint)Keyboard.Qualifiers.KEY_BASE_CODE);
            if ((key & (uint)Keyboard.Qualifiers.KEY_CTRL) != 0  && (c == 'c')) {
                        len = 1; 
                        buffer[0] = (char) Pipe.ControlCodes.CTRL_C;  // ctrl-X
                        DebugStub.WriteLine("tty: CTRL_C detected");
                    }
                    else if ((key & (uint)Keyboard.Qualifiers.KEY_CTRL) != 0  && c == 'z') {
                        len = 1; 
                        buffer[0] = (char) Pipe.ControlCodes.CTRL_Z;  // ctrl-X
                        DebugStub.WriteLine("tty: CTRL_Z detected");
                    }
            else if (c == '\b') {
                len = 1; 
                buffer[0] = c;
            }
            else if (c == '\n') {
                len = 1; 
                buffer[0] = c;
                // echo
                // Console.WriteLine();
            }
            else { 
                // Only use the character if it's in the printable ASCII range
                if ((c >= 32) && (c <= 126)) // SPACE to "~"
                {
                    //Console.WriteLine("char={0}:{1:x}",c,key);
                    len = 1; 
                    buffer[0] = c; 
                    // echo
                    // Console.Write(c);
                }
                else if ((c >= Keyboard.Keys.PAGE_UP) && (c <= Keyboard.Keys.DELETE)) {
                    //Console.WriteLine("tty: generating esc sequence for:{0:x}",key); 
                    buffer[0] = (char) 0x1b;
                    buffer[1] = '[';
                    int pos = 2; 
                    
                    switch ((int) c) {
                        case Keyboard.Keys.PAGE_UP: 
                            buffer[pos++] = '5';
                            buffer[pos++] = '~';
                            break; 
                        case Keyboard.Keys.PAGE_DOWN: 
                            buffer[pos++] = '6';
                            buffer[pos++] = '~';
                            break; 
                        case Keyboard.Keys.UP_ARROW: 
                            buffer[pos++] = 'A';
                            break; 
                        case Keyboard.Keys.DOWN_ARROW: 
                            buffer[pos++] = 'B';
                            break; 
                        case Keyboard.Keys.LEFT_ARROW: 
                            buffer[pos++] = 'D';
                            break; 
                        case Keyboard.Keys.RIGHT_ARROW: 
                            buffer[pos++] = 'C';
                            break; 
                        case Keyboard.Keys.HOME: 
                            buffer[pos++] = '1';
                            buffer[pos++] = '~';
                            break; 
                        case Keyboard.Keys.END:
                            buffer[pos++] = '4';
                            buffer[pos++] = '~';
                            break; 
                        case Keyboard.Keys.INSERT: 
                            buffer[pos++] = '2';
                            buffer[pos++] = '~';
                            break; 
                        case Keyboard.Keys.DELETE: 
                            buffer[pos++] = '3';
                            buffer[pos++] = '~';
                            break; 
                    }
                    len  = pos;
#if false                    
                    DebugStub.Write("tty: esc seq ="); 
                    for (int i = 0; i < len; i++) {
                        DebugStub.Write(" {0}",__arglist(buffer[i]));
                    }
                    DebugStub.WriteLine(""); 
#endif                     
                }
            }
            
            return buffer;  
        }

        private static void InputWorkerThread() 
        {
            UnicodePipeContract.Imp! stdinImp =  inputEp.Acquire(); 
            KeyboardDeviceContract.Imp:Ready! keyboard = keyboardRef.Acquire(); 
            char[] in ExHeap buffer = new [ExHeap] char [10]; 
            
            WaitForChildContract.Imp! imp;
            WaitForChildContract.Exp! exp;
            WaitForChildContract.NewChannel(out imp, out exp);

            new Thread(new ThreadStart(new WaitForChildThread(
                process, new TRef<WaitForChildContract.Exp:Start>(exp))
                .Wait)).Start();

            uint key = 0;
            while (true) {
                keyboard.SendGetKey();
                switch receive {
                    case imp.Finish():
                        delete buffer;
                        goto done; 
                    case keyboard.AckKey(ikey):
                        key = ikey;
                        break;
                    case keyboard.NakKey():
                        break;
                    case keyboard.ChannelClosed():
                        Tracing.Log(Tracing.Debug, "Keyboard channel closed");
                        delete buffer;
                        goto done;

                }
                //DebugStub.WriteLine("input:{0:x}",__arglist(key)); 

                // process key
                if ((key & (uint)Keyboard.Qualifiers.KEY_DOWN) == 0) {
                    continue;
                }
                if ((key & (uint)Keyboard.Qualifiers.KEY_MOUSE) != 0) {
                    continue;
                }
 
                int len; 
                buffer = ProcessKey(key, buffer, out len);
                
                if (len > 0) {
                    stdinImp.SendWrite(buffer,0,len);
                    
                    switch receive {
                    case stdinImp.AckWrite(i_buffer):
                        buffer = i_buffer; 
                        break;
                    case stdinImp.ChannelClosed():
                        DebugStub.WriteLine("tty: stdin closed");
                        Tracing.Log(Tracing.Debug, "stdin channel closed");
                        DebugStub.Break();  //this should not happen! 
                        goto done;
                    }
                }
                
            }
        done:
            delete stdinImp;
            delete keyboard;
            delete imp; 
        }

        ///////////////////
        // process escape sequence embedded in output buffer
        // pos is the index of the escape character in the buffer
        private static char[] escBuf; 
        
        private static int HandleEscape(ConsoleDeviceContract.Imp! console,
                                         char[]! in ExHeap buffer, int pos, int len)
        {
            Pipe.EscapeCodes  code;      
            int column, row, repeat;
            
            int i; 
            terminal.Reset(); 
            repeat = 0;
            
            code = Pipe.EscapeCodes.NOCODE; 
            
            int limit;
            if (pos + len < buffer.Length) limit = pos + len; 
            else limit = buffer.Length;
            for (i = pos; i < limit; i++) {
                bool more = terminal.ProcessEscape(buffer[i], out code, out repeat); 
                if (!more) break; 
            }
            
            switch (code) {
            case Pipe.EscapeCodes.UP:
                console.SendGetCursorPosition();
                console.RecvCursorPosition(out column, out row);
                if (row > 0) {
					console.SendSetCursorPosition(column, row-1);
					console.RecvAckSetCursorPosition();
					//DebugStub.WriteLine("tty: up received. shifting from row {0}, col {1}",__arglist(row, column));
                }
                else {
					DebugStub.WriteLine("tty: cannot move up; already at top");
                }
                break;
            case Pipe.EscapeCodes.LEFT:
                console.SendGetCursorPosition();
                console.RecvCursorPosition(out column, out row);
                if (column > 0) {
					console.SendSetCursorPosition(column-1, row);
					console.RecvAckSetCursorPosition();
					//DebugStub.WriteLine("tty: left received. shifting from row {0}, col {1}",__arglist(row, column));
                }
                else if (row > 0) {
					// Move up one row and to the end.
					console.SendSetCursorPosition(_console_columns - 1, row - 1);
					console.RecvAckSetCursorPosition();
                }
                else {
					DebugStub.WriteLine("tty: already at origin, cannot move left");
                }
                break;
            case Pipe.EscapeCodes.RIGHT:
                //DebugStub.WriteLine("tty: right received");
                console.SendGetCursorPosition();
                console.RecvCursorPosition(out column, out row);
                if (column + 1 < _console_columns) {
	                console.SendSetCursorPosition(column+1, row);
		            console.RecvAckSetCursorPosition();
		        }
		        else if (row + 1 < _console_rows) {
					console.SendSetCursorPosition(0, row+1);
					console.RecvAckSetCursorPosition();
		        }
		        else {
					DebugStub.WriteLine("tty: already at end of screen!");
				}
                break;
            case Pipe.EscapeCodes.ERASE_FROM_CURSOR:
                //DebugStub.WriteLine("tty: ERASE FROM CURSOR received");
                console.SendClearCursorToEndOfLine(); 
                console.RecvAckClearCursorToEndOfLine(); 
                break; 
            case Pipe.EscapeCodes.CLEAR_SCREEN:
                console.SendClear();
                console.RecvAckClear();
                break; 
            case Pipe.EscapeCodes.SET_CURSOR_SIZE:
                //DebugStub.WriteLine("tty: ERASE FROM CURSOR received");
                bool ignore = false; 
                Microsoft.Singularity.Io.CursorSize  size = Microsoft.Singularity.Io.CursorSize.Small; 
                switch (repeat) {
                case 1: 
                    size = Microsoft.Singularity.Io.CursorSize.Small;
                    break; 
                case 2:
                    size = Microsoft.Singularity.Io.CursorSize.Large;
                    break; 
                default: 
                    break; 
                    ignore = true; 
                }
                if (!ignore) {
                    console.SendSetCursorSize(size); 
                    switch receive {
                    case console.AckSetCursorSize():
                        break; 
                    case console.NotSupported(): 
                        break; 
                    }
                }
                break; 
            case Pipe.EscapeCodes.NOCODE: 
                break;
            }
            return i;
        }
        
        private static void OutputWorkerThread() 
        {
            UnicodePipeContract.Exp! stdoutExp = outputEp.Acquire(); 
            ConsoleDeviceContract.Imp! console = consoleRef.Acquire();

            bool pipeActive  = true; 
            int pos; 
            int newPos = 0;
            
            try { 
                while (pipeActive) {
                    switch receive {
                        case stdoutExp.Write(buffer, index, count):
                            // inspect each key looking for escape sequences
                            // if any are found split up the buffer logically into
                            // 3 parts (pre, escape, and post). All three will need to be 
                            // sent separately. 
                            // Need to ensure the correct buffer gets back to the caller
                            assert buffer.Length >= (index + count);
                            for (pos = 0; pos < count; pos++) {
                                if (buffer[pos + index] == (char) 0x1b) break; 
                            }
                            int pre; 
                            int post; 
                            if (pos != count) {
                                if (pos == 0 && count == 1) {
                                    // ignore single escape char -- should never be sent
                                    pre = 0; 
                                    post = 0; 
                                }
                                else { 
                                     newPos = HandleEscape(console,buffer,pos+1, count);  
                                     pre = pos - index; 
                                     post = (pos+count-1) - newPos; 
                                } 
                                
                                if (pre != 0) {
                                    char [] in ExHeap preBuf = new [ExHeap] char [pre]; 
                                    for (int i = 0; i < pre; i++) {
                                        preBuf[i] = buffer[index+i];
                                    }
                                        // write all chars before 
                                    console.SendWrite(preBuf, 0, pre);
                                    
                                    switch receive {
                                    case console.AckWrite(localside): 
                                        // performing a partial write need to save the buffer 
                                        delete localside;
                                        break;
                                        
                                    case console.NakWrite(localside):
                                        // Unicode contract has no negative ack
                                        stdoutExp.SendAckWrite(localside);
                                        break;

                                    case console.ChannelClosed():
                                        pipeActive = false; 
                                        break;
                                    }
                                }
                                
                                if (post != 0) {
                                    char [] in ExHeap postBuf = new [ExHeap] char [post]; 
                                    for (int i = 0; i < post; i++) {
                                        postBuf[i] = buffer[newPos+i];
                                    }
                                    console.SendWrite(postBuf, 0, newPos);
                                    switch receive {
                                    case console.AckWrite(localside):
                                        delete localside;
                                        break;
                                        
                                    case console.NakWrite(localside):
                                        // Unicode contract has no negative ack
                                        stdoutExp.SendAckWrite(localside);
                                        break;

                                    case console.ChannelClosed():
                                        pipeActive = false; 
                                        break;
                                    } 
                                } 
                                stdoutExp.SendAckWrite(buffer);
                            }  // escape sequence 

                            else { 
                            console.SendWrite(buffer, index, count);
                            switch receive {
                            case console.AckWrite(localside):
                                stdoutExp.SendAckWrite(localside);
                                break;
                                
                            case console.NakWrite(localside):
                                // Unicode contract has no negative ack
                                stdoutExp.SendAckWrite(localside);
                                break;

                            case console.ChannelClosed():
                                pipeActive = false; 
                                break;
                            }                      
                            }     
                            break;
                        case stdoutExp.ChannelClosed():
                            pipeActive = false; 
                            break;
                    }
                }
            }
            finally {
                delete stdoutExp;
                delete console;
            }
        }

        private static int RunShellProcess(String[] args)
        {
            assert args != null; 
            assert args[0] != null; 
            
            DebugStub.WriteLine("Starting {0}, argcount={1}", __arglist( args[0], args.Length));
            Console.WriteLine("Starting {0}, argcount={1}", args[0], args.Length);
            // create shell process with stdin/out bound to us
            //process = new Process(args, null, 2);
            process = new Process((!)args[0], null, null); 
         
            UnicodePipeContract.Imp! stdinImp;
            UnicodePipeContract.Exp! stdinExp;
            UnicodePipeContract.NewChannel(out stdinImp, out stdinExp);
            
            UnicodePipeContract.Imp! stdoutImp;
            UnicodePipeContract.Exp! stdoutExp;
            UnicodePipeContract.NewChannel(out stdoutImp, out stdoutExp);

            process.SetStartupEndpoint(0, (Endpoint * in ExHeap) stdinExp);
            // hack 
            process.SetStartupEndpoint(1, (Endpoint * in ExHeap) stdoutImp);
            
            // new style pass in args via StringArrayParameter
            if (args.Length > 1) {
                    String[]! shellArgs = new String[args.Length - 1];
                    Array.Copy(args, 1, shellArgs, 0, shellArgs.Length);
                    process.SetStartupStringArrayArg(0, shellArgs);
            }
            
            process.Start();

            // start our output thread
            // We need a multiplexer, if we want to echo input characters in tty.
            UnicodePipeContract.Imp! localStdoutImp;
            UnicodePipeContract.Exp! localStdoutExp;
            UnicodePipeContract.NewChannel(out localStdoutImp, out localStdoutExp);

            PipeMultiplexer! pm = PipeMultiplexer.Start(localStdoutImp, stdoutExp);
            
            inputEp = new TRef<UnicodePipeContract.Imp:READY> (stdinImp);
            outputEp = new TRef<UnicodePipeContract.Exp:READY> (localStdoutExp);

            // Connect our own console output to the output multiplexer
            UnicodePipeContract.Imp ttyStdout = pm.FreshClient();
            UnicodePipeContract.Imp oldStdout = ConsoleOutput.Swap(ttyStdout);
            // oldStdout is likely null, because the tty does not get a stdout on startup
            delete oldStdout;

            // start up output thread to handle input and output 
           
            ThreadStart output = new ThreadStart(OutputWorkerThread); 
            Thread outThread = new Thread(output);
            outThread.Start();

            // run input copier on this thread
            InputWorkerThread();
            // dispose the pipe multiplexer. This should shut down the output thread
            pm.Dispose();

            outThread.Join();
            return process.ExitCode; 
        }

        // TODO: better ways to wait on a child process
        private class WaitForChildThread
        {
            private Process! process;
            private TRef<WaitForChildContract.Exp:Start>! expRef;

            internal WaitForChildThread(Process! process, TRef<WaitForChildContract.Exp:Start>! expRef)
            {
                this.process = process;
                this.expRef = expRef;
                base();
            }

            internal void Wait()
            {
                process.Join();
                WaitForChildContract.Exp exp = expRef.Acquire();
                exp.SendFinish();
                delete exp;
            }
        }
        
        public static int Main(String[] args)
        {
            // TODO: get ns from startup endpoints
            DirectoryServiceContract.Imp ns = DirectoryService.NewClientEndpoint();
            // get access to the real keyboard
            KeyboardDeviceContract.Imp keyboard = OpenKeyboard("/dev/keyboard", ns); 
            if (keyboard == null) {
                DebugStub.WriteLine("Console Input: Couldn't open keyboard.");
                DebugStub.Break(); 
                delete ns;
                return -1;
            } 
            ConsoleDeviceContract.Imp console;
            console = OpenConsole("/dev/video-text", ns);
            if (console == null) {
                console = OpenConsole("/dev/conout", ns);
                if (console == null) {
                    DebugStub.WriteLine("Couldn't open console.\n");
                    DebugStub.Break(); 
                    delete keyboard;
                    delete ns;
                    return -1;
                }
            }
            delete ns;
            
            // Query the size of the display.
            // This is useful later on.
            console.SendGetDisplayDimensions();
            int columns;
            int rows;
            console.RecvDisplayDimensions(out columns, out rows);
            _console_columns = columns;
            _console_rows = rows;
            
            terminal = new Terminal(); 
            InitModTable(); 
            keyboardRef = new TRef<KeyboardDeviceContract.Imp:Ready>(keyboard);
            consoleRef = new TRef<ConsoleDeviceContract.Imp:Ready>(console);
            
            string [] shellArgs; 
            if (args == null || args.Length < 2) { 
                shellArgs = new string[1]; 
                shellArgs[0] = "shell"; 
            }
            else {
                shellArgs = new string[args.Length -1];
                Array.Copy(args, 1, shellArgs, 0, shellArgs.Length);
            }
            int code = RunShellProcess(shellArgs); 

            return code; 
        }
        
        static int _console_columns;
        static int _console_rows;
    } //Tty
    
}//namespace